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Locomotives 

Locomotive engines are significant contributors to air 

pollution in many of our nation's cities and ports.

Although locomotive engines being produced today 

must meet relatively modest emission requirements 

set in 1997, they continue to emit large amounts of

nitrogen oxides and particulate matter (PM), both of 

which contribute to serious public health problems.

In May 2004, as part of the Clean Air Nonroad Diesel 

Rule, EPA finalized new requirements for nonroad diesel fuel that will decrease the allowable 

levels of sulfur in fuel used in locomotives by 99 percent. These fuel improvements will create 

immediate and significant environmental and public health benefits by reducing PM from 

existing engines. 

In March 2008, EPA finalized a three part program that will dramatically reduce emissions 

from diesel locomotives of all types -- line-haul, switch, and passenger rail. The rule will cut 

PM emissions from these engines by as much as 90 percent and NOx emissions by as much 

as 80 percent when fully implemented. 

This final rule sets new emission standards for existing locomotives when they are 

remanufactured--to take effect as soon as certified systems are available, as early as 2008. 

The rule also sets Tier 3 emission standards for newly-built locomotives, provisions for clean 

switch locomotives, and idle reduction requirements for new and remanufactured 

locomotives. Finally, the rule establishes long-term, Tier 4, standards for newly-built engines 

based on the application of high-efficiency catalytic aftertreatment technology, beginning in 

2015. 

This page provides general and technical information on the locomotive rulemakings that 

affect railroads, locomotive manufacturers, and remanufacturers. 

Regulations and Guidance

2008 Locomotive and Marine Diesel Engines Emission Standards 

2005 Technical Amendments 

Idling Locomotives 

1997 Rulemaking and Supporting Data 

Related Links 

Regulations and Guidance 

See the electronic Code of Federal Regulations (e-CFR) for the full text 

of current regulations that apply to locomotives. The documents 

related to the rulemaking that established these provisions are 

available below. 

NOTE: You will need 

Adobe Acrobat 

Reader, available as 

a free download, to 

view some of the 

files on this page. 

See EPA's PDF page

Nonroad Engines, Equipment, and Vehicles Last updated on Tuesday, December 1st, 2009.

http://www.epa.gov/otaq/locomotives.htm#2008final

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Final Rule: Control of Emissions of Air Pollution from 

Locomotives and Marine Compression-Ignition Engines

Less Than 30 Liters per Cylinder (published May 6, 2008 

and republished June 30, 2008) 

Fact Sheets: 

EPA Finalizes More Stringent Emissions Standards 

for Locomotive Engines and Marine Compression-Ignition Engines | PDF 

Version (5 pp, 144K, March 2008, EPA420-F-08-004) 

Emission Factors for Locomotives (PDF) (9 pp, 260K, April 2009, EPA420-F-09-

025) 

Final Rule (republished June 30, 2008) 

Pages 37095-37144 | PDF Version (50 pp, 1,063K) 

Pages 37145-37194 | PDF Version (50 pp, 1,246K) 

Pages 37195-37244 | PDF Version (50 pp, 917K) 

Pages 37245-37294 | PDF Version (50 pp, 1,253K) 

Pages 37295-37344 | PDF Version (50 pp, 1,260K) 

Pages 37345-37350 | PDF Version (6 pp, 157K) 

Final Rule (published May 6, 2008) 

Preamble and 40 CFR Parts 85-94 (Pages 25097-25146) | PDF Version (50 

pp, 364K) 

Pages 25147-25196 | PDF Version (50 pp, 1,141K) 

Pages 25197-25246 | PDF Version (50 pp, 922K) 

Pages 25247-25296 | PDF Version (50 pp, 1,347K) 

Pages 25297-25346 | PDF Version (50 pp, 1,316K) 

Pages 25347-25352 | PDF Version (6 pp, 158K) 

Regulatory Impact Analysis (PDF) (739 pp, 10MB, May 2008, EPA420-R-08-001a) 

Summary and Analysis of Comments (PDF) (463 pp, 2.4MB, March 2008, EPA420-F08-006) Instead of downloading the entire document, you can access the 

individual chapters of the Summary and Analysis of Comments. 

See the Proposed Rule (published April 3, 2007) and the Advance Notice of 

Proposed Rulemaking (published June 29, 2004) for the rules, fact sheets, and 

technical support documents. 

Final 2005 Technical Amendments – Procedures for Testing Highway and 

Nonroad Engines and Omnibus Technical Amendments (published July 13, 

2005) 

Fact Sheet: Regulatory Announcement: Changed Test Procedures for Nonroad 

Engines and Heavy-Duty Highway Engines | PDF Version (4 pp, 134K, EPA420-F-05-

036, July 2005) 

Final Rule (published July 13, 2005): 

Pages 40419-40468 | PDF Version (50 pp, 949K) 

Pages 40469-40518 | PDF Version (50 pp, 938K) 

Pages 40519-40568 | PDF Version (50 pp, 6.1MB) 

Pages 40569-40614 | PDF Version (50 pp, 1.81MB) 

Technical Support Document and Summary & Analysis of Comments (PDF) (115 

pp, 1.7MB, EPA420-R-05-008, June 2005) 

See Proposed Technical Amendments for the proposed rule, fact sheet, and 

technical support documents (published September 10, 2004). 

Idling Locomotives Fact Sheet: Control of Emissions from Idling Locomotives | 

PDF Version (4 pp, 98K, March 2008, EPA420-F-08-014) 

1997 Locomotive Emissions Final Rulemaking (published December 17, 1997) 

Read First (2K, TXT) 

Final Rule published April 16, 1998 (consists of three separate files) 574K PDF, 

466K PDF, 60K PDF and 

317K TXT, 336K TXT, 55K TXT 

Docket Listing (PDF) (61K) 

Summary Analysis of Comments (WP5 ZIP file) (135K) 

Regulatory Support Document (PDF) (3.9MB)

to learn more about 

PDF, and for a link 

to the free Acrobat 

Reader.

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RSD Appendices A&C-P (PDF) (2.4MB)

RSD Appendix B and data used in other appendices (WK3 file) (184K) 

Fact Sheets: 

Requirements for Railroads Regarding Locomotive Exhaust Emission 

Standards (PDF) (94K) 

Applicability of Locomotive Emission Standards (PDF) (78K) 

Final Emission Standards for Locomotives (PDF) (19K) 

Environmental Benefits of Emission Standards for Locomotives (PDF) (39K) 

Federal Preemption of State and Local Standards for Locomotives (PDF)

(11K) 

Emission Factors for Locomotives (PDF) (31K) Also see newer version from 

2008 rule. 

See the Proposed Rule (published January 31, 1997). 

Future Nonroad Emission Reduction Credits for Locomotives (January 1995) (TXT)

(7K) 

Related Links: 

Compliance Fees 

Certification Data 

Federal Railroad Administration, U.S. Department of Transportation 

Clean Diesel Programs 

Nonroad Diesel Equipment 

Diesel Fuel 

Marine Remanufacture Program (See this Fact Sheet for information about certifying a 

locomotive remanufacture kit for use with marine engines.) 

For more information, please email EPA's Assessment and Standards Division

(asdinfo@epa.gov) or call the Assessment and Standards Division voicemail at 734-214-

4636. 

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